Some of our customers (and users on several support forums) have complained about trouble with mail sync since they started using iOS 8's default Mail app: https://discussions.apple.com/thread/6541881
Please be aware that SaneBox processes are not involved in whatever problems cause the iOS 8.x Mail app to not sync mail folder contents for some with email accounts on certain Exchange server versions their providers use.
As seen via the above link, some users have reported resolving sync problems by:
- resetting Network Settings (Settings app | Reset | Network..)
- and/or removing the email account and then adding it back,
with cellular data turned off and WiFi on instead,
for a fresh entry of the email account
('Mail, Contacts & Calendars' in iOS 8 Settings app).
Some have also reported discovering that their MS Exchange server is set up where the provider has policies to limit the number of devices and require those with new phones to remove old ones (form in settings via OWA webmail) to be under that limit before adding a new device.
Be assured, posts in these forums are from a cross-section of Exchange users, most of whom have yet to use SaneBox. We have also had a very small number of bug reports from SaneBox customers (thank you!) who have experienced Exchange sync problems after changing to the iOS 8 Mail app. Unfortunately it's not something we can control, otherwise we'd be able to fix it.
For a process of elimination while considering any sort of email trouble, you can use the 'Pause' button from your dashboard to temporarily stop SaneBox processing on an email accoount and see that a problem is unrelated: https://www.sanebox.com/dashboard/settings
We'll keep close watch for further reports or developments on these issues.